Markup to margin converter

Inputs: cost plus exactly one of markup or margin

Margin is gross margin as a percent of selling price: twenty means twenty percent of the list price is profit. Cost must be strictly positive; zero or negative cost is rejected because selling-price formulas divide by cost when recovering markup. Negative markup or margin percentages are out of scope for this retail converter and fail validation. Margin must stay strictly below one hundred percent; the special case of margin equal to one hundred percent is called out in the error message because one minus margin over one hundred becomes zero and selling price is undefined. All checks run before any money math, so bad requests never produce a half-filled price row. Send a JSON body with a required positive cost and exactly one percentage field. Cost is the acquisition or production amount in any single currency you already track—aliases cost_price, cogs, wholesale, and purchase_price are accepted when your client already names the field differently. Markup is the uplift expressed as a percent of that cost: twenty-five means twenty-five percent markup, so selling price equals cost times one plus markup over one hundred. Aliases markup_percent, markup_pct, and mu map to markup; margin_percent, margin_pct, gross_margin, and ma map to margin. Provide exactly one of the two rates—both present or both missing fails with invalid_input so the engine never has to guess which number is authoritative. Extremely large costs or markups are capped so Worker isolate arithmetic stays bounded.

How markup, margin, selling price, and profit are computed

Money fields cost, selling_price, and profit are rounded half-up to two decimal places so results look like currency on a quote rather than long binary fractions. Percentage fields are rounded with a fine stable scale so goldens and SDK demos pin cleanly. The response echoes normalized cost, both percentages, selling_price, profit, a solved flag equal to margin or markup naming which rate was derived, method equal to markup_margin, and a formulas object documenting the four identities for UI tooltips. Use markup alone when buyers speak in cost-plus language; use margin alone when finance speaks in gross-margin targets; use selling_price when a storefront needs the list amount. Identical inputs always produce identical JSON because the path is pure arithmetic with no network, no random seed, and no wall clock.

API usage, pricing, retail workflows, and practical limits

Call the free in-browser markup to margin converter for shelf pricing workshops, vendor negotiations, and classroom exercises without installing a spreadsheet. Keep costs within ordinary commercial ranges; extreme values are rejected so isolate math stays bounded. The product promise is the classical single-item markup-versus-margin conversion with an explicit guard against one-hundred-percent margin—not multi-product baskets, promotional stacking, or dynamic competitor matching, which belong in specialized tools with different SEO intent. Use the prepaid API when a catalog importer, ERP connector, ecommerce rule engine, or pricing chatbot needs a stable KIT contract at $0.002 per successful item; validation failures never consume balance after the engine rejects the request. Pair this endpoint with currency converters only if you already know amounts in one currency—this capability does not convert FX, apply sales tax, or layer shipping. Authors shipping SDKs can map markup, margin, selling_price, and profit directly into pricing tables and quote builders.